High Availability Flashcards
How do you load balance to multiple applications n the same machine?
Use an Application Load Balancer
Using Application Load Balancer, how can we get the client IP, the port and the proto?
X-Forwarded-For, X-Forwarded-Port and X-Forwarded-Proto
What traffic does an Application Load Balancer handle?
Layer 7 HTTP/HTTPS and Websocket
What traffic does a Network Load Balancer handle?
Layer 4 TCP
How do you enable Stickiness?
In the target group, under Attributes, select the stickiness attributes to apply
What are 4 attributes of the Application Load Balancer?
- Layer 7 HTTP Traffic
- URL based routing with hostname/path
- Does not support static IP, has a DNS
- Provides SSL Termination
What are 4 attributes of Network Load Balancer?
- Layer 4 TCP
- No pre-warming needed
- 1 static IP per subnet
- No SSL termination - SSL must be enabled at app level
What is one way to assign a static IP to an ALB?
Put a Network Load Balancer in front of it
What should you do if you expect high traffic to hit your ALB?
Open a support ticket with AWS to pre-warm the ALB
How would you support SSL for Legacy Browsers?
Change the ALB Policy to allow for the weaker cipher:
ELBSecurityPolicy-TLS-1-0-2015-04
What are 4 Load Balancer troubleshooting steps?
- Check Security Groups
- Check Health Checks
- Check Sticky Sessions are not imbalanced
- For Multi-AZ, make sure cross zone balancing is enabled
What is SurgeQueueLength?
The total number of requests/connections that are pending routing to an instance.
What is MaxValue of the SurgeQueueLength?
1024
What is the SpillOverCount?
The total number of requests rejected because the Surge Queue is full
What are the 8 Scaling processes in Auto Scaling Groups?
- Launch
- Terminate
- HealthCheck
- ReplaceUnHealthy
- AZRebalance
- AlarmNotifcation
- ScheduledActions
- AddToLoadBalancer
